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humidistat. If using this profile, the blower will run at
75% airflow for the first 10 minutes of each cooling
cycle.The basic cooling/heat-pump speed should be
selected at or near the top of the range for that nominal
capacity. See Table 3.
Demand Defrost control
The demand defrost board controls the defrost cycle
in response to ambient temperature, outdoor coil
temperature and accumulated compressor run time. The
heat pump is allowed to operate in the heating mode
until the combination of outdoor ambient and outdoor
coil temperatures indicate that defrosting is necessary,
based on the programmed defrost curve. There are four
preprogrammed defrost curves on the board.
• A jumper pin is used to switch between the different
curves. The default jumper position is curve 1 and is the
recommended setting for most standard applications.
See Table 5 for additional defrost curves settings.
• The factory default setting does not include a 30
second compressor delay function and has a 40 ° F
defrost terminate temperature. If additional defrost time
is needed, a higher terminate temperature is available
by selecting a different demand curve. noTe: The
30 second compressor delay function is optional and
based on the demand curve selected.
• The standard defrost cycle will terminate after 13
minutes and 39 seconds or when the coil temperature
reaches its terminate temperature, whichever occurs
first.
• The defrost board is equipped with a 5 minute Anti-
Short Cycle Delay (ASCD). The compressor will not
turn on until it reaches the minimum 5 minute off time.
• The control contains a forced - defrost feature, which
places the system into defrost mode every 6 hours
and 4 minutes, unless the coil temperature is above
the selected terminate temperature.
• The system can be manually forced into defrost
mode at any time by shorting the TeST terminals on
the demand defrost board together for more than 9
seconds. The coil temperature sensor does not need
to be cold when the unit is forced into defrost. After the
TeST input is removed, the defrost mode will terminate
in 13.7 minutes, if the coil temperature is above the
terminate set-point, or when the Y input is removed,
whichever occurs first.
noTe: If a demand curve is selected which has a 30
second compressor time delay in defrost, the delay is
reduced to 10 seconds in TEST mode.
minimum Time
Jumper
between Defrosts
Position
(min)
1
20
2
20
3
20
4
20
Table 5. Demand Defrost curve Profiles
optional comfort alert
TM
The Comfort Alert
Diagnostics Module is a breakthrough
innovation for troubleshooting heat pump and air
conditioning system failures. The module installs easily in
the electrical box of the outdoor unit near the compressor
contactor. By monitoring and analyzing data from the
Copeland scroll compressor and the thermostat demand,
the module can accurately detect the cause of electrical
and system related failures without any sensors. A
flashing LED indicator communicates the ALERT code
and a diagnostic key is also imprinted on the side of the
module to quickly direct the technician to the root cause
of a problem. See Figure 6 (page 12).
noTe: This module does not provide safety protection!
The Comfort Alert
TM
Diagnostics Module is a monitoring
device and cannot control or shut down other devices.
24 VAC Power Wiring
TM
The Comfort Alert
module requires a constant nominal
24 VAC power supply. The module cannot be powered by
the c terminal on a defrost board or other control board
without experiencing nuisance alerts. noTe: The wiring
to the module's R & c terminals must be routed directly
from the transformer.
Thermostat Demand Wiring
The Comfort Alert module requires a two stage thermostat
to operate properly. The Y2 thermostat wire entering
the unit should be connected to the Y2 input on the unit
terminal strip.
While the compressor is running, Comfort Alert will provide
power to the second stage cooling solenoid inside the
compressor after Y2 has been energized for 5 seconds.
When the compressor is not running, Comfort Alert will
not power the solenoid, regardless of the state of Y2. If
Alert codes 1 or 9 appear while the compressor is running,
Comfort Alert will turn off the solenoid to prevent solenoid
damage from overheating conditions.
L Terminal Wiring
The l connection is used to communicate Alert codes to
compatible White-Rodgers thermostats. The l terminal
of the thermostat should be connected directly to the
Comfort Alert l terminal.
On some White-Rodgers thermostats, an icon on the
thermostat display will flash at the same rate as the
Comfort Alert yellow Alert LED. An advanced option on
Terminate
30 second
Temperature
compressor
(° F)
Delay Function
40
no
40
YES
75
NO
75
YES
Tm
Diagnostics module
11
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Table of Contents
Troubleshooting
